Apparatus for finishing die nibs

ABSTRACT

A turntable has means for securing thereto a drawing die, the encased nib of which has an axial hole therethrough. A cylinder surrounding the die and extending upwardly from the table holds a slurry of abrasive particles in an electrolyte. A lapping tool is suspended eccentrically in the hole in the nib for contact with the surface defining the hole. The tool is mounted on a crank arm projecting from a sleeve journaled on a vertical shaft. A second arm extending from said sleeve is engaged by a bell crank to apply torque thereto. A cooling-spray pipe extends around the cylinder and an annular collecting trough is disposed below the lower edge of the latter. An agitator supported from outside the cylinder projects thereinto.

March 7, 1972 J, w, KEILSQ 3,647,669

APPARATUS FOR FINISHING DIE NIBS Filed May 26, 1969 2 Sheets-Sheet l INVENTOR. JOHN W. KELSO March 7, 1972 J. w. KELSO 3,647,659

' APPARATUS FOR FINISHING DIE NIBS Filed May 26, 1969 2 Sheets-Sheet 2 FIG. 4.

v v v v v v v v v v v, 932 364 9931 mum/ram JOHN w. KEL so LAPP/NG SUSPENSION A H. rn ey United States Patent U.S. Cl. 204212 1 Claim ABSTRACT OF THE DISCLOSURE A turntable has means for securing thereto a drawing die, the encased nib of which has an axial hole therethrough. A cylinder surrounding the die and extending upwardly from the table holds a slurry of abrasive particles in an electrolyte. A lapping tool is suspended eccentrically in the hole in the nib for contact with the surface defining the hole. The tool is mounted on a crank arm projecting from a sleeve journaled on a vertical shaft. A second arm extending from said sleeve is engaged by a bell crank to apply torque thereto. A cooling-spray pipe extends around the cylinder and an annular collecting trough is disposed below the lower edge of the latter. An agitator sup-ported from outside the cylinder projects thereinto.

This invention relates to electrolytic die-lapping apparatus and, in particular, to apparatus including a turntable with means for securing thereto a die comprising an encased nib, the nib having a hole therethrough, with the hole disposed vertically.

The most pertinent prior art of which I am aware is Engle Patent No. 2,385,198.

It is the general object of m invention to provide dielapping apparatus equipped for electrolysis of the liquid in which the lapping abrasive is suspended.

SUMMARY OF THE INVENTION A preferred embodiment of my invention includes a base having a turntable carried on a spindle journaled vertically on the base. A cylindrical side wall extends upwardly from the turntable, surrounding means for securing a die thereon. A lapping tool depends eccentrically into the hole in the nib of the die, from an overhead arm extending from a sleeve journaled on a vertical shaft. A second arm extending from the sleeve is engaged by torque-applying means causing the lapping tool yieldably to engage the surface of the hole through the die nib. A spray ring surrounds the cylindrical wall and an annular collecting trough extends around it below the lower edge thereof.

BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawmgs:

FIG. 1 is a perspective view of my apparatus, with parts broken away;

FIG. 2 is a partial vertical section taken through the die being finished, showing in elevation the lapping tool by which the operation is performed;

FIG. 3 is a horizontal section through the tool taken on the plane of line IIIIII of FIG. 2;

FIG. 4 is a vertical section through the turntable, cylinder and die showing the lapping tool in elevation;

FIG. 5 is an enlarged partial section through the tool and die nib showing the Working clearance therebetween at the line of closest approach; and

FIG. 6 is a perspective view of a detail.

3,647,669 Patented Mar. 7, 1972 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the drawings, my apparatus, indicated generally at 10, is mounted on a base 11 and comprises a spindle :12 journaled vertically thereon so as to be driven by a gearmotor '13 on the base. A turntable 14 is mounted on the spindle and is provided with a clamping ring 15 and bolts 16 whereby a die 17 including an encased nib 18 may be secured thereon coaxially with spindle 12. A collector ring 19 is secured on the spindle and a brush 20 suitably supported engages it for making electrical connection to the spindle from a conductor 21.

A cylindrical side wall 22 extends upwardly from turntable 14, forming a holder for a slurry of abrasive particles such as diamond dust or boron nitride and an electrolyte such as sodium nitrite plus a thickener, e.g., ethylene glycol. A cooling-spray ring 23 suitably supported, extends around wall .22 and has ports circumferentially spaced therearound for discharging sprays of cooling liquid from a suitable source onto the exterior thereof. An annular collecting trough 24, suitably supported, extends around the lower edge of wall 22. A set of agitator or churning blades 25 extends down inside wall 22 from an adjacent supporting post 2 6.

A tool post 27 is upstanding on a plate 28 resting on base .11 but electrically insulated therefrom by a mat 29 of suitable material. A crank sleeve 30 is journaled on the upper end of post 27 and has radial crank arms 31 and 32 extending in opposite directions at right angles thereto. At the outer end of arm 31 is a tool holder 33. A lapping tool 34 has its shank secured in holder 33 by a set screw 35 and depends into the hole formed through die nib 18. Tool 34, of course, has the shape which it is desired to impart to the hole in the finishing operation. When the tool is brought eccentrically into working relation with the surface defining the hole, as shown in FIIGS. 2 and 3, and lapping suspension is fed therebetween, as shown in FIG. 5, the finishing of the nib to the desired surface shape is rapidly accomplished, aided by electrolysis. For this purpose the tool holder 33 has secured thereto a terminal for a conductor 37.

On roation of the turntable, the lapping suspension in holder 22 is churned up by blades 25 and fed to the die nib as shown by the arrows in FIG. 4. Coolant may be sprayed on the holder and collected in trough 24.

To bring the tool eccentrically into working relation with the surface of the hole in the die nib, a bell crank 38 is pivotally mounted on plate 218. One arm 39 of the crank has a pin 40 therethrough on which counterweights 41 are removably disposed. The other arm 42 of the crank bears against crank arm 32 and applies torque to sleeve 30. This forces the tool 34 laterally of the hole in the die nib. Contact pin 40 is adapted to engage a contact plate on a wedge 43 slidable on plate 28 by a screw 44 and having a nut thereon which is part of a worm and wormwheel drive 45 through which a motor 46 actnates the screw. Thus the movement of the tool is limited to the desired range, and may be made repetitious to engage the nib periodically.

Tool .34 may be adjusted to bring different portions of its surface close to the surface of the hole in the nib for lapping coaction, by loosening screw 35 and turning the tool through a small angle.

It will be evident that my invention is simple yet effective in operation and easy to maintain. The principal advantage, however, is that it is capable of finishing die nibs accurately with but little attention.

I claim:

1. Apparatus for finishing die nibs having a hole therethrough comprising a turntable, means for securing a die nib coaxially on the turntable, a holding cylinder extending upwardly from said turntable and surrounding said nib, a spray ring surrounding said cylinder, a stationary collecting trough extending around said cylinder below the lower edge thereof, means mounting stationary agitator blades inside said cylinder, means mounting a lapping tool eccentrically in working relationship to said nib and electrical connections to said turntable and tool, means exerting a force on said tool urging it against the surface of the hole through the nib, and means for adjusting the force exerted by said force-exerting means, said force-exerting means including a crank sleeve journaled on a vertical axis, a crank arm extending from said sleeve and means exerting torque on said second arm tending to turn said sleeve.

References Cited UNITED STATES PATENTS 10 JOHN H. MACK, Primary Examiner R. J. FAY, Assistant Bentley et al. 204-143 M X Engle 204-143 G Bowersett 204-212 Schwartz, Jr 204 -212 Fromson 204-143 M X Mikoshiba et al. 204-224 X Examiner US. Cl. X.R. 

